1. Field of the Invention
The present invention relates to an electronic control unit storing therein vehicle identification information, which is unique on a vehicle-by-vehicle basis. The present invention also relates to a vehicle control system.
2. Description of Related Art
A modern vehicle is equipped with a vehicle control system, which includes multiple electronic control units (also called ECUs) for controlling parts of the vehicle. As is described in JP-2001-301572A for example, a specific one of the ECUs rewritably stores a vehicle identification number (also called a VIN code), which is unique on a vehicle-by-vehicle basis, in a non-volatile memory thereof such as an EEPROM (electrically erasable and programmable read only memory) and the like.
When the ECU storing the VIN code is detached from one vehicle and is re-mounted in a different vehicle, the VIN code in the ECU is rewritten. The VIN code is used for identification of a vehicle when, for example, a dealer repairs a vehicle. Through the identification of a vehicle, the dealer can provide a more suitable treatment that matches a type of the vehicle.
In connection with a vehicle control system, OBD-II (On-Board Diagnostics II) issued by CARB (California Air Resources Board) requires that malfunction information indicative of vehicle malfunction be stored in a non-volatile memory, which is for example an EEPROM or a continuously-powered memory such as standby RAM (random access memory), SRAM (static random access memory) and the like. Because of this requirement, malfunction information is stored in a non-volatile memory of each ECU in a vehicle control system.
OBD-II also requires that when the VIN code is rewritten, all of malfunction information associated with an emission system be erased at the same time. Because of this requirement, it is necessary to reliably erase the emission-related malfunction information when rewriting the VIN code stored in a specific ECU.
The inventor of the present application has found that a conventional way of erasing malfunction information in ECUs involves the following difficulty. In the conventional way, after the VIN code is rewritten, an instruction for erasing the malfunction information is inputted to each ECU from an external tool. However, if an ECU is powered-off or reset during erasure of the malfunction information, the malfunction information in the ECU remains unerased although the rewrite of VIN code has been completed. This may lead to violation of the requirement of OBD-II.